Process and installation for the distribution of air enriched in oxygen to passengers of an aircraft

ABSTRACT

According to this process, there is supplied to the passengers a first fraction of air enriched in oxygen from independent supply elements, in particular high pressure cylinders ( 16 ), during a descent phase of the aircraft between a normal cruising altitude and an intermediate rerouting altitude. There is moreover compressed air taken from a source of compressed air belonging to the aircraft, to produce (in  2 ) a second fraction of the air enriched in oxygen which is delivered to the passengers, at least during a phase of stabilized flight of the aircraft, adjacent the re-routing altitude, greater than 5,500 meters.

BACKGROUND OF THE INVENTION

The present invention relates to a process and an installation for thedistribution of air enriched in oxygen to the passengers of an aircraft,more particularly a commercial airliner.

During accidental depressurization of the cabin of an airplane, at highaltitude, the occupants (passengers and crew) must rapidly inhale airenriched in oxygen, so as to avoid a condition of hypoxia, due to theabrupt decrease in the partial pressure of oxygen.

To this end, it is known to provide independent means, permittingsupplying air enriched in oxygen. It can be high pressure cylinders, inwhich is stored pure oxygen. Alternatively, it can be produced by meansof chemical oxygen generators.

The distribution of oxygen to the passengers, from supply means, takesplace by means of masks. These latter permit a mixture of distributedoxygen and ambient air. Distribution is stopped when the aircraftregains a low altitude of about 3,000 meters, which is reached about 15minutes from a beginning altitude of about 12,500 meters.

This known solution however has certain drawbacks.

In particular, given that, in the case of depressurization, the aircraftmust necessarily regain a relatively low altitude, about 3,000 meters,it is indispensable to retain in the fuel tanks a supplemental fuelquantity. Thus, the consumption of the aircraft is increased at this lowaltitude, because of the greater air resistance. It will be easily beseen that the carrying of this supplemental fuel contributes toincreasing the weight of the apparatus significantly.

SUMMARY OF THE INVENTION

The invention proposes to use a process for the distribution of airenriched in oxygen, permitting overcoming this drawback.

To this end, it has for an object a process for the distribution of airenriched in oxygen to passengers of an aircraft, in which there issupplied to the passengers a first fraction of air enriched in oxygenfrom an independent source, during a descent phase of the aircraftbetween a cruising altitude and a re-routing altitude, and there isproduced, in an onboard separator, a second air fraction enriched inoxygen, which is delivered to the passengers, at least during asubstantially stabilized phase of the flight of the aircraft, takingplace at about the re-routing altitude.

The invention permits achieving the objects mentioned above.

Thus, according to the invention, the onboard separator can produce airenriched in oxygen, from a source of compressed air belonging to theaircraft, for a very great period of time. The passengers are thus ableto be supplied with air enriched in oxygen, not only during the time ofdescent, but also during the re-routing flight itself.

It will thus be easily seen that the altitude of rerouting can, becauseof this fact, be substantially greater than that of the prior art.Thanks to the process of the invention, it is thus possible to be ableto re-route at altitudes greater than 5,500 meters, preferably comprisedbetween 6,000 and 8,000 meters, permitting avoiding most of the highmountains on earth. By way of comparison, with the process using thesolution of the prior art, such a rerouting altitude would requiresupply means, such as cylinders or generators, whose size and mass wouldbe unacceptable.

Moreover, the quantity of reserve fuel, which must be kept in tanks ofthe aircraft, is substantially reduced thanks to the invention. Thus,the re-routing altitude permitted by the invention gives rise to asubstantial decrease in the consumption of fuel relative to the priorart, which requires achieving a much lower altitude. The reduction ofthis supplemental quantity of fuel thus ensures a corresponding decreasein the weight of the aircraft, as well as its consumption. Moreover,this reduction of volume of onboard fuel permits the carrying ofadditional occupants or baggage, which is economically advantageous.

Given that the invention permits higher rerouting altitudes, it permits,as mentioned above, airline companies to design new routes, overflyingmountainous regions. Such a possibility of advantageous to the extent towhich it is able to reduce the duration of the flights. It should beremembered that the routes referred to above are up to the presentforbidden, when they fly above regions whose altitude is greater thanthe re-routing altitude permitted by the prior art.

Finally, the invention permits avoiding the transportation of heavygaseous oxygen cylinders or overdimensioned onboard oxygen generators.This guarantees a decrease in weight of the apparatus, and considerablyreduces the risks of explosion during onboard fires.

The invention also has for its object an installation for supplying airenriched in oxygen to the passengers of an aircraft, comprising anindependent source of a first fraction of air enriched in oxygen,onboard means for the production of a second fraction of air enriched inoxygen, means to deliver the first and second fractions of air enrichedin oxygen to the passengers, and means (14) for sequential distributionof the respective flows of the first and second fractions of airenriched in oxygen to the delivering means (20, 22, 23).

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described below, with reference to theaccompanying single FIGURE, given solely by way of non-limiting example,this FIGURE being a schematic view showing one embodiment of aninstallation for the distribution of air enriched in oxygen according tothe invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The distillation installation shown in this FIGURE comprises a separatoror concentrator of oxygen of known type, designated overall by thereference numeral 2. This concentrator, which permits a separation ofthe oxygen and the nitrogen contained in the air typically usingmolecular sieves, particularly zeolites, of a type known per se. Thisconcentrator supplies at its outlet air enriched in oxygen with anoxygen content preferably between 60 and 95%, typically between 80 and93%, at a low pressure typically comprised between 1.5 and 2.5 barsgauge.

This concentrator 2 is connected by a line 4 provided with a filter 6,with a source 7 of compressed air within an airplane. Such a source isfor example comprised by the air conditioning circuit of the aircraft,or else by removal from the compressor stage of the reactors.

The concentrator 2 comprises an outlet conduit 8, within whichcirculates air enriched in nitrogen, as well as a line 10, within whichcirculates the air enriched in oxygen. This line 10 is provided with adetector 12, permitting monitoring the oxygen content of the enrichedair which circulates in it.

In the illustrated embodiment, the line 10 opens into a three-way valve14, that communicates moreover via a conduit 16 with a battery of gascylinders 18. These latter ensure, in a conventional way, the storage ofpure oxygen under high pressure greater than 110 bars gauge, typicallybetween 120 and 150 bars. They can be complemented, as the case may be,by chemical oxygen generators (not shown) which are also of known type.A conduit 16 comprises at least one regulator/expander (not shown) tosupply to the line 20 oxygen under a reduced pressure, below 3 barsgauge.

The outlet of the three-way valve 14 is constituted by a distributionline 20, running along the airplane cabin and which is divided intoseveral branches 22 of which each is adapted to supply an oxygen mask 23for one passenger. This line 20 is provided with a pressure regulator24, which permits evenly distributing the quantity of air distributed tothe assembly of the branches 22.

Finally, there is provided an altimeter 26, co-acting with actuationmeans (not shown), permitting controlling the valve 14, via the line 28.As a modification, this altimeter could be replaced or supplemented by apressure detector.

The operation of the installation described above will be explained inthe following.

At cruising altitude, for example about 12,500 meters, the line 20 isnot supplied, neither by the concentrator 2, which is on standby, nor bythe cylinders 18.

During a depressurizing accident, a signal is sent conventionally to thepilot. This latter thus initiates the immediate opening of the cylinders18, so as to supply the line 20 with enriched air, from the conduit 16and via the three-way valve 14. This guarantees the immediatedistribution to the passengers of a first fraction of air enriched inoxygen, by means of branches 22, terminating in oxygen masks 23.

Moreover, the pilot simultaneously starts the oxygen concentrator 2,which requires a startup time of several minutes. Given that, duringthis startup, the three-way valve is in communication solely with theconduit 16, and not with the line 10, it is necessary to provide anoutlet for evacuation of the air produced initially by the concentrator.Such an evacuation (not shown in the drawing) can be located in thethree-way valve 14, or else upstream of the latter in the supply line10.

When the predetermined rerouting altitude is reached, typically above5,000 meters, preferably between 6,000 to 8,000 meters, the detector 26causes the swinging of the three-way valve 14, which then places incommunication the line 20 with the concentrator 2, via the line 10. Inthis way, the masks receive, via the supply line 20 and its branch 22, asecond fraction of air enriched in oxygen, supplied by the concentrator2.

The second fraction of air has a high oxygen content, between 60 and95%, preferably between 80 and 93%. This air enriched in oxygen isdiluted with ambient air at the mask 23, during inhaling by theoccupant, to reconstitute the oxygen content suitable to the altitude ofthe rerouted flight (between 26% for an altitude of 5,500 meters and 40%for an altitude of 8,000 meters), which avoids having to supply largeflow rates at the outlet of the concentrator.

Once these oxygen masks 23 are supplied by the concentrator, the flightis adapted to continue at the pre-selected rerouting altitude for aperiod of time limited only by the kerosene supply of the airplane.

What is claimed is:
 1. Installation for the distribution of air enrichedin oxygen to passengers of an aircraft, comprising: an independentsource of a first fraction of air enriched in oxygen; onboard means forthe production of a second fraction of air enriched in oxygen; means fordelivering the first and second fractions of enriched air to thepassengers; and means for the sequential distribution of the respectiveflows of the first and second fractions of air enriched in oxygen, tothe delivery means, wherein the distribution means comprises a firstinlet connected to the independent source, a second inlet connected tothe production means, and an outlet connected to the delivery means, andwherein the distribution means comprises a three-way valve. 2.Installation according to claim 1, wherein the production meanscomprises a molecular sieve concentrator.
 3. Installation for thedistribution of air enriched in oxygen to passengers of an aircraft,comprising: an independent source of a first fraction of air enriched inoxygen; onboard means for the production of a second fraction of airenriched in oxygen; means for delivering the first and second fractionsof enriched air to the passengers; means for the sequential distributionof the respective flows of the first and second fractions of airenriched in oxygen, to the delivery means; and means sensitive to thecontrol pressure of the distribution means, wherein the regulation meanscomprises a three-way valve.
 4. Installation according to claim 1,wherein the independent source comprises oxygen cylinders underpressure.